Intellectual property comes of age as an alternative investmentFOR those who got burned investing in bricks and mortar, it may be time for a punt on property of a more intellectual kind. Patents have traditionally been the domain of wild-haired inventors and computer geeks. These days they are just as likely to attract the interest of slick investors, from hedge funds and private-equity firms to venture capitalists and even distressed-debt funds. What was once viewed as a stodgy legal asset is fast becoming a sought-after financial one.The market is still small but it is growing quickly—by perhaps 20-30% a year, reckons Coller Capital, an investment firm that has snapped up, among other prizes, IBM’s portfolio of medical-device and health-care patents. Intellectual Ventures, based near Seattle, has spent a large chunk of the $5 billion it has raised from investors on buying patents; at the last count it had 27,000. Fortress, a big hedge-fund and private-equity group, is also active. Ron Epstein of iPotential, a patent-brokerage firm, says he is getting an ever-increasing volume of calls from hedge funds looking for patents related to mobile telecoms, medical equipment, biotechnology and the internet. He estimates that $4 billion-worth were bought and sold last year overall. ...